Real Salt Lake Academy's Axel Kei made his professional debut at age 13 on Friday night in Herriman, Utah.
The Ivory Coast-born striker was a second-half substitute for the USL Championship side Real Monarchs, entering in the 61st minute of a 0-0 draw against Colorado Springs Switchbacks FC.
At 13 years, nine months and nine days old, Kei is believed to be the youngest-ever player to make a professional appearance in American team sports.
In July, Kei led RSL Academy to the Under 15 MLS NEXT Cup championship with a 2-0 win against Philadelphia Union Academy. He won the Golden Boot at the event with five goals.